When asked if the country great would ever play for an audience again, his wife, Kim Woolen, 55, says it's unlikely.

"He can't even tune a guitar now. If I tune one and hand it to him he can still play, [but] not like he used to," Woolen told PEOPLE at the Open Hearts Foundation's 4th Annual Gala in Malibu on Saturday. However, he can still "play a couple licks here and there, and he finds joy in that."

Now living in a memory-care facility near their Nashville home, the "Rhinestone Cowboy" singer, 78, spends his days looking at pictures and chatting with Woolen, who visits him "every single day for hours."

"It's a very nurturing place … [and] he feels secure there," she says. "I sit with him through his meals … we hug each other and cuddle. I savor every day."

And though it's been "absolutely heartbreaking" for the Campbell family (the couple have three children together), they've tried to stay positive.

"There's a lot of sadness, [but] we just continue to try to make the best of every day and keep a sense of humor," says Woolen.